Methods for dynamic servo optimization based on tape position

Embodiments of the present disclosure generally relate to a tape head module assembly and a tape drive including the tape head module assembly.

Tape heads of tape drive systems are used to record and read back information on tapes by magnetic processes. Magnetic transducers of the tape heads read data from and write data onto magnetic recording media. Data is written on the magnetic recording media by moving a magnetic write transducer to a location over the media where the data is to be stored. The magnetic write transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by the magnetic read transducer through sensing of the magnetic field of the magnetic media.

As data is written to and read from a magnetic tape, the magnetic tape moves back and forth between a cartridge reel and a take-up reel. However, the angular speed or rotations per minute (RPM) of the two reels is constantly changing during read and write operations, causing dynamic lateral tape motion (LTM) along the magnetic tape. The LTM introduces dynamic disturbances along the tape in both magnitude and frequency directions. As such, the tape head struggles to accurately read and write data.

Therefore, there is a need in the art for a tape drive able to adjust its control strategy according to dynamic LTM.

The present disclosure is generally related to a tape drive comprising a tape head, the tape drive being configured to read from and/or write to a tape. There are pre-written magnetic patterns on the tape. One or more servo readers will read the patterns and generate read-back signals. A control program is embedded in a SoC/FPGA/CPU to decode the read-back signals and control the head to follow the track. Position Error Signal (PES) is the signal that describes the difference between the head position and the target position, thus the criteria of wellness of head control. As a manufacturing process, the tape drive comprises a processor configured to perform a disturbance profile identification detecting one or more disturbances along a length of a tape in a frequency domain of the PES. The disturbance profile identification is used to create a peak filter array, which is used to instruct the voice coil motor and/or piezoelectric actuators to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance. In some embodiments, the generated filter array is further configured to align with a plurality of tape zones partitioned based on the size of the filter array. Servo parameters in the processor that is used to control a servo head are then updated based on the filter array within each zone to change the tape head control strategy specific to each zone. Utilizing the disturbance profile identification helps the tape head track following along the tape that has unique dynamic disturbances.

In one embodiment, a tape drive comprises a take-up reel and a cartridge reel configured to have a tape coupled thereto, a tape head configured to write data to and read data from the tape, a first actuator, a second actuator, the first and second actuators each configured to actuate the tape head, and a processor configured to: perform a reel rotation per minute (RPM) disturbance profile identification detecting one or more disturbances in a frequency domain of position error signal (PES) along a length of a tape, acquire exact information of the disturbance points by applying a filter based on prior information, acquire the longitudinal position (LPOS), frequency, and magnitude of the one or more disturbances to create an updated disturbance profile identification, and use the updated disturbance profile identification to create a peak filter array that will be buffered in a memory device. During write or read operations, the peak filter array is used to assist in instructing one or more of the first actuator and the second actuator to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during a read or a write operation.

In another embodiment, a tape drive comprises a take-up reel and a cartridge reel configured to have a tape coupled thereto, a tape head configured to write data to and read data from the tape, a first actuator, a second actuator, the first and second actuators each configured to actuate the tape head, and a processor coupled to the tape head, the processor comprising servo controller parameters, wherein the processor is configured to: perform a reel rotation per minute (RPM) disturbance profile identification detecting one or more disturbances along a length of a tape, partition the tape longitudinally into a plurality of zones based on the size of a peak filter array, create data write gaps at the boundaries between each of the zones, and update servo parameters when the tape head crosses each boundary when writing data to or reading data from the tape.

In yet another embodiment, a tape drive comprises a take-up reel and a cartridge reel configured to have a tape coupled thereto, a tape head configured to write data to and read data from the tape, a first actuator, a second actuator, the first and second actuators each configured to actuate the tape head, and a processor coupled to the tape head, the processor comprising controller servo controller parameters, wherein the processor is configured to: perform a reel rotation per minute (RPM) disturbance profile identification detecting one or more disturbances along a length of a tape based on prior information, acquire exact information of the disturbance points by applying a filter, and acquire the longitudinal position (LPOS), frequency, and magnitude of the one or more disturbances to create an updated disturbance profile identification. In some embodiments, the generated filter array is further configured to align with a plurality of tape zones partitioned based on the size of the filter array. the processor is configured to: use the peak filter array to assist in instructing one or more of the first actuator and the second actuator to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during a read operation or a write operation, partition the tape longitudinally into a plurality of zones based on the peak filter array, create data write gaps at the boundaries between each of the zones, and update the servo parameters when the tape head crosses each boundary when writing data to or reading data from the tape, the updated servo control parameters being based on the peak filter array generate.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

In the following, reference is made to embodiments of the disclosure. However, it should be understood that the disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the disclosure. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the disclosure” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

The present disclosure is generally related to a tape drive comprising a tape and a tape head. The tape drive comprises a processor configured to perform a disturbance profile identification detecting one or more disturbances along a length of a tape. The disturbance profile identification is used to create a peak filter array, which is used to instruct the voice coil motor and/or piezoelectric actuators to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during a read or a write operation. In some embodiments, the generated filter array is further configured to align with a plurality of tape zones partitioned based on the size of the filter array. Servo parameters of a servo head are then updated based on the peak filter array within each zone to adjust the control strategy specific to each zone. Utilizing the disturbance profile identification prevents a track following capability loss against the dynamic lateral tape motion of the tape drive.

1 1 FIGS.A-C 1 FIG.B 1 FIG.C 1 FIG.A 100 100 105 110 120 125 127 130 135 135 155 155 105 a b illustrate a perspective exploded view, a simplified top down, and side profile view of a tape drive, in accordance with some embodiments. The tape drivemay be a captive tape drive or a tape embedded drive (TED). Focusing on, for example, the tape drive comprises a casing, one or more tape reels, one or more motors (e.g., a stepping motor(also known as a stepper motor), a voice coil motor (VCM), a piezoelectric (PZT) actuator, a head assemblywith one or more read heads and one or more write heads, and tape guides/rollers,. In the descriptions herein, the term “head assembly” may be referred to as “magnetic recording head”, interchangeably, for exemplary purposes. Focusing on, for example, the tape drive further comprises a printed circuit board assembly (PCBA). In an embodiment, most of the components are within an interior cavity of the casing, except the PCBA, which is mounted on an external surface of the casing. The same components are illustrated in a perspective view in. In the descriptions herein, the term “tape” may be referred to as “magnetic media”, interchangeably, for exemplary purposes.

110 105 110 130 110 110 115 110 110 115 110 110 100 110 100 100 115 110 115 100 115 115 115 115 In the illustrated embodiments, two tape reelsare placed in the interior cavity of the casing, with the center of the two tape reelson the same level in the cavity and with the head assemblylocated in the middle and below the two tape reels. Tape reel motors located in the spindles of the tape reelscan operate to wind and unwind the tape mediain the tape reels. Each tape reelmay also incorporate a tape folder to help the tape mediabe neatly wound onto the reel. One or more of the tape reelsmay form a part of a removable cartridge and are not necessarily part of the tape drive. For example, one of the reelsis a cartridge reel and the other is the take-up reel. In such embodiments, the tape drivemay not be a tape embedded drive as it does not have embedded media, the drivemay instead be a tape drive configured to accept and access magnetic media or tape mediafrom an insertable cassette or cartridge (e.g., an LTO drive), where the insertable cassette or cartridge further comprises one or more of the tape reelsas well. In such embodiments, the tape or mediais contained in a cartridge that is removable from the drive. The tape mediamay be made via a sputtering process to provide improved areal density. The tape mediacomprises two surfaces, an oxide side and a substrate side. The oxide side is the surface that can be magnetically manipulated (written to or read from) by one or more read/write heads. The substrate side of the tape mediaaids in the strength and flexibility of the tape media.

115 110 135 135 135 130 110 135 135 135 130 115 135 130 115 130 a b a b a b Tape mediafrom the tape reelsare biased against the guides/rollers,(collectively referred to as guides/rollers) and are movably passed along the head assemblyby movement of the reels. The illustrated embodiment shows four guides/rollers,, with the two guides/rollersfurthest away from the head assemblyserving to change direction of the tape mediaand the two guides/rollersclosest to the head assemblyby pressing the tape mediaagainst the head assembly.

1 FIG.A 1 FIG.B 135 135 As shown in, in some embodiments, the guides/rollersutilize the same structure. In other embodiments, as shown in, the guides/rollersmay have more specialized shapes and differ from each other based on function. Furthermore, a lesser or a greater number of rollers may be used. For example, the two function rollers may be cylindrical in shape, while the two functional guides may be flat-sided (e.g., rectangular prism) or clip shaped with two prongs and the film moving between the prongs of the clip.

125 120 120 125 115 The voice coil motorand stepping motormay variably position the tape head(s) transversely with respect to the width of the recording tape. The stepping motormay provide coarse movement, while the voice coil motormay provide finer actuation of the head(s). In an embodiment, servo data may be written to the tape media to aid in more accurate position of the head(s) along the tape media.

105 141 142 1 FIG.A In addition, the casingcomprises one or more particle filtersand/or desiccants, as illustrated in, to help maintain the environment in the casing. For example, if the casing is not airtight, the particle filters may be placed where airflow is expected. The particle filters and/or desiccants may be placed in one or more of the corners or any other convenient place away from the moving internal components. For example, the moving reels may generate internal airflow as the tape media winds/unwinds, and the particle filters may be placed within that airflow.

100 105 115 105 115 105 105 130 110 There is a wide variety of possible placements of the internal components of the tape drivewithin the casing. In particular, as the head mechanism is internal to the casing in certain embodiments, the tape mediamay not be exposed to the outside of the casing, such as in conventional tape drives. Thus, the tape mediadoes not need to be routed along the edge of the casingand can be freely routed in more compact and/or otherwise more efficient ways within the casing. Similarly, the head(s)and tape reelsmay be placed in a variety of locations to achieve a more efficient layout, as there are no design requirements to provide external access to these components.

1 FIG.C 105 150 145 155 105 150 155 105 105 115 As illustrated in, the casingcomprises a coverand a base. The PCBAis attached to the bottom, on an external surface of the casing, opposite the cover. As the PCBAis made of solid state electronics, environmental issues are less of a concern, so it does not need to be placed inside the casing. That leaves room inside casingfor other components, particularly, the moving components and the tape mediathat would benefit from a more protected environment.

100 105 In some embodiments, the tape driveis sealed. Sealing can mean the drive is hermetically sealed or simply enclosed without necessarily being airtight. Sealing the drive may be beneficial for tape film winding stability, tape film reliability, and tape head reliability. Desiccant may be used to limit humidity inside the casing.

150 100 150 145 100 In one embodiment, the coveris used to hermetically seal the tape drive. For example, the drivemay be hermetically sealed for environmental control by attaching (e.g., laser welding, adhesive, etc.) the coverto the base. The drivemay be filled by helium, nitrogen, hydrogen, or any other typically inert gas.

100 155 130 141 142 In some embodiments, other components may be added to the tape drive. For example, a pre-amp for the heads may be added to the tape drive. The pre-amp may be located on the PCBA, in the head assembly, or in another location. In general, placing the pre-amp closer to the heads may have a greater effect on the read and write signals in terms of signal-to-noise ratio (SNR). In other embodiments, some of the components may be removed. For example, the filtersand/or the desiccantmay be left out.

100 140 140 140 140 140 In various embodiments, the driveincludes controllerintegrated circuits (IC) (or more simply “a controller”) (e.g., in the form of one or more System on Chip (SoC)), along with other digital and/or analog control circuitry to control the operations of the drive. For example, the controllerand other associated control circuitry may control the writing and reading of data to and from the magnetic media, including processing of read/write data signals and any servo-mechanical control of the media and head module. In the description below, various examples related to writing and reading and verifying of written data, as well as control of the tape head and media to achieve the same, may be controlled by the controller. As an example, the controllermay be configured to execute firmware instructions for the various same gap verify embodiments described below.

2 FIG. 1 1 FIGS.A-C 200 204 200 202 204 204 200 200 214 204 200 240 140 is a schematic illustration of a tape head module assemblyand a tapethat are aligned. The tape head module assemblycomprises a tape head bodythat is aligned with the tape. The tapemoves past the tape head module assemblyduring read and/or write operations. The tape head module assemblyhas a media facing surface (MFS)that faces the tape. The tape head module assemblyis coupled to a controller, which may be the controllerof.

202 206 206 208 208 206 206 202 The tape head bodycomprises a first servo element pairA and a second servo element pairB spaced therefrom. It is to be understood that while two servo element pairs have been shown, the disclosure is not limited to two servo element pairs. Rather, it is contemplated that more or less servo element pairs may be present. A plurality of data headsA-G is disposed between the first servo element pairA and the second servo element pairB. It is to be understood that while seven data heads have been shown, the disclosure is not limited to seven data heads. Rather, the number of data heads can be more or less than seven, depending on the requirements of the embodiment. For example there can be sixteen, thirty two, sixty four or more data heads utilized in the tape head body.

220 220 202 220 220 202 220 220 206 206 220 220 200 2 FIG. A plurality of padsA-N is electrically coupled to the data head body. The plurality of padsA-N coupled to the data head bodyis not limited to the number shown in. Rather, more or less pads are contemplated. The padsA-N are used to connect the drive electronics to the servo element pairsA,B and to data read and writer elements. The padsA-N are used to establish the potential across the servo reader by means of a power supply (not shown) embedded in the tape head.

204 210 210 210 210 200 208 208 212 212 204 The tapecomprises a first servo trackA and a second servo trackB. The first servo trackA and the second servo trackB are spaced apart allowing the tape headto monitor and control the average position of the data headsA-G relative to the data tracksA-G on the tape. It is to be understood that while two servo tracks have been shown, the disclosure is not limited to two servo tracks. Rather, the number of servo tracks can be more or less than two, depending on the requirements of the embodiment.

204 212 212 210 210 206 210 206 210 200 208 208 208 204 208 208 212 212 206 206 210 210 208 208 212 212 204 2 FIG. The tapefurther comprises a plurality of data tracksA-G disposed between the first servo trackA and the second servo trackB. It is to be understood that while seven data tracks have been shown, the disclosure is not limited to the seven data tracks. Rather, the number of data tracks can be more or less than seven, depending on the requirements of the embodiment. In the embodiment of, the first servo element pairA reads its lateral position information (e.g., alignment) over the first servo trackA. The second servo element pairB is aligned with the second servo trackB. The combined information allows the servo actuator of the tape driveto align the data headsA-G such that the center data head (e.g.,D) is centered on tape. The plurality of data headsA-G is thus individually aligned with the plurality of data tracksA-N for best case positioning. In this embodiment the first servo element pairA, the second servo element pairB, the first servo trackA, the second servo trackB, the plurality of data headsA-G, and the plurality of data tracksA-G are able to read and/or write the data accurately because all are aligned perpendicular to the direction of travel of the tape.

3 3 FIGS.A-B 1 1 FIGS.A-C 300 350 300 350 100 140 300 350 illustrate methods,for correcting dynamic lateral tape motion (LTM) in a tape drive, according to embodiments disclosed herein. The methods,may be utilized with the tape driveof, such as being executed by the controller. The methodsandmay be used in combination with one another.

300 302 Methodbegins at operation, where, prior to performing write and read operations, a reel rotation per minute (RPM) disturbance profile identification is performed, where one or more disturbances are detected along a length of a tape (i.e., from a beginning of the tape (BOT) to an end of the tape (EOT)). A position of the tape head and the tape are also decoded from the pre-written servo pattern. Position error signals (PESs) are calculated based on the difference between the position of tape head and the target position. The disturbance information is further identified based on prior or known information, such as reel radius and tape speed. The reel RPM disturbance profile identification may be performed at a factory or in the field, and may be performed numerous times while the tape moves at different speeds. The disturbance information may be stored in a table and are identified in the table by their corresponding longitudinal position (LPOS) along the length of the tape.

304 428 4 FIG. At operation, a filter is applied to one or more disturbances' frequency to acquire additional information of the disturbances, including frequency and magnitude of the disturbances. The frequency and magnitude of the disturbances are used to calculate new specific servo control parameters, such as a peak filter array. The filter array and the corresponding LPOS of the disturbances are stored in a table. The table may be stored in memory, such as the memoryshown in. The servo control parameters may also include tape speed, and tape head tilt, for example. The servo parameters are calculated in a factory setting in one embodiment, but may be calculated or updated in the field as needed.

306 306 At operation, the LPOS, frequency, and magnitude of the disturbances are acquired to calculate or generate an updated disturbance profile identification. Operationmay further include changing position signals of the LPOS from a time domain to a frequency domain. The updated disturbance profile identification may be further used to generate a peak filter array that can be stored in a look-up table, such as with the calculated servo parameters, and the table may be stored in memory. The applied filter that is used to create disturbance profile is based on known parameters of the tape drive, such as the speed and radius of the reels, the rotation frequency, harmonics, the tape length, and the tape thickness. The applied filter that is used to create disturbance profile may be a band pass filter, a low pass filter, or a high pass filter, for example.

4 FIG. 3 FIG.A 304 308 300 400 400 400 300 400 420 422 424 426 428 illustrates a process flow of a system on a chip (SoC), an integrated circuit (IC), or a field-programmable gate array (FPGA) utilized in the operations-of the methodof, according to one embodiment. For simplicity, the SoC, IC, or FGPA will be referred to herein as circuitor processor. The circuitis used to implement aspects of the method. The circuitis configured to use a filterto acquire additional information of a disturbance that can be used to generate peak detection, from which a disturbance profile of the detected disturbance pointsis created, leading to the generation of servo controller parameters, which enables the tape drive's servo control system to be tailored to the dynamic disturbances, and to store the controller parameters in the memoryfor storage of updated disturbance profile identification.

308 300 310 608 654 656 600 630 632 634 650 630 632 6 FIG.A 6 FIG.A 6 6 FIGS.A-B 6 6 FIGS.A-B a a b b At operationof method, the updated disturbance profile identification is used to create a peak filter array, which is a factory setting lookup table, and is based on the disturbance profile. At operation, the peak filter array is used to calibrate and generate instructions for the controllers of the PZT actuator(shown in) and/or VCM actuator(s),(shown in) in order to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during write and read operations. In one embodiment, the PZT controller(shown in) comprises 3 peak filters,,to help adjust the frequency, and the VCM controller(shown in) comprises 2 peak filters,to help adjust the frequency. While 2 and 3 peak filters are shown, the controllers may comprise any number of peak filters.

5 FIG. 3 FIG.A 500 300 500 x x illustrates an exemplary tablecomprising the peak filter array generated in the methodof, according to one embodiment. As shown, the tablecomprises the LPOS of each disturbance point, along with one or more servo parameters and disturbance information. The servo parameters are simply represented as (A-N), where x is a numeral identifying the peak filter parameters (i.e., 1-5 in the present example), and A-N represents the number of servo parameters.

6 FIG.A 1 1 FIGS.A-C 2 FIG. 601 601 100 200 illustrates a block diagram of a servo control loopof a tape head, according to one embodiment. The servo loopmay be utilized with the tape driveof, and/or with the tape head module assemblyof.

601 602 600 604 650 650 652 640 640 606 608 654 656 654 656 654 656 654 656 656 654 The servo loopcomprises a stepping motor controller, a PZT controller, a PZT estimator, a LTM controller, which may be a VCM controller, a tilt controller, and an actuator and amplifier system. The actuator and amplifier systemcomprises a stepping motor, a PZT actuator, and two VCM actuators,, where when both VCM actuators,move upward, the tape head moves upward accordingly; when both VCM actuators,move downward, the head moves downward. If the left VCM actuatormoves downward while the right VCM actuatormoves upwards (with a greater force or displacement), the tape head tilts toward the left side; conversely, the tape head tilts toward the right side when the right VCM actuatormoves downward while the left VCM actuatormoves upwards.

602 606 600 650 606 608 604 608 650 Target commands (cmd) for each band are sent the stepping motor controller, which then instructs the stepping motorto move or re-position to target a data band. PES are input into the PZT controllerand the LTM controller. The PZT controllerthen provides the calculated control effort to the PZT actuatorand the PZT estimator, which estimates the tape head displacement by the PZT actuator, and provides the estimates to the LTM controller.

650 652 654 656 604 654 656 606 608 654 656 602 600 650 652 Similarly, the LTM controllerand the tilt controllerare configured to instruct the VCM actuatorsandto move or re-position as desired based on the PES input and the estimates the displacement provided from the PZT estimator. The VCM actuators,then move based on a calculated control effort, move in a cross-track direction, or tilt as needed to compensate for any LTM. The instructions provided to the stepping motor, the PZT actuator, and the VCM actuators,are then output to correctly position the various actuators as instructed by the controllers,,,.

6 FIG.B 3 FIG.A 6 FIG.A 6 FIG.A 1 FIG.B 6 FIG.A 1 FIG.B 600 650 300 600 650 601 600 608 127 650 654 656 125 600 630 632 634 636 638 650 630 632 656 658 660 630 632 634 600 650 a a b b a a illustrates the PZT controllerand the VCM controllerused in the output of the methodof, according to one embodiment. The PZT controllerand the VCM controllermay be part of the servo head controllerof. The PZT controlleris configured to control the PZT actuatorof(and/or the PZT actuatorof), and the VCM controlleris configured to control the VCM actuators,of(and/or the VCM actuatorof). The PZT controllercomprises a first peak filter, a second peak filter, a third peak filter, an integrator, and a notch. The VCM controllercomprises a first peak filter, a second peak filter, an integrator, a notch, and a lead. The LPOS of the disturbance points and the peak filter array are input to the first, second, and third peak filters,,to serve as a lookup value from which one or more output values or servo control parameters are determined in order to instruct the PZT actuator controlled by the PZT controllerand the VCM actuator controlled by the VCM controllerto individually move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during a read or a write operation.

7 7 FIGS.A-D 3 FIG.A 700 725 750 775 300 700 725 750 767 illustrate graphs,,,showing how the peak filter array is used to adjust the frequency and/or amplitude of the disturbances targeting the disturbance points at a frequency domain using the methodof, according to one embodiment. In the graphs,,,, the y-axis is magnitude (mag) in dB and the x-axis is frequency in Hz.

7 FIG.A 7 FIG.B 7 FIG.C 7 FIG.D 700 725 700 750 725 775 725 illustrates a graphshowing the sensitivity of tape head control.illustrates a graphshowing the peak filter array being applied to the initial or base frequency of the graph.illustrates a graphshowing how the amplitude of the disturbance point is adjustable using the peak filter array of the graph. The arrow shown illustrates how the amplitude is adjustable along the y-axis.illustrates a graphshowing how the frequency of the disturbance point is adjustable using the peak filter array of the graph. The arrow shown illustrates how the frequency is adjustable along the x-axis. By applying the peak filter array, both the amplitude and frequency of disturbance points can be adjusted as needed to minimize the impact of the disturbance caused.

350 302 500 428 300 350 302 300 350 3 FIG.B 5 FIG. Methodofbegins at operation, where, prior to performing write and read operations, a reel rotation per minute (RPM) disturbance profile identification is performed, where one or more disturbance points are detected in the frequency domain along a length of a tape (i.e., from a beginning of the tape (BOT) to an end of the tape (EOT)). A position of the tape head and the tape are also decoded from the pre-written servo pattern. Position error signals (PESs) are calculated based on the difference between the position of tape head and the target position. The disturbance profile identification is used to generate a peak filter array that is stored in a table, such as the tableof, in memory. As stated above, methodsandcould be used in combination, and operationmay be the same in each method,.

354 308 800 812 812 812 812 812 812 812 812 3 FIG.A 8 FIG. 8 FIG. 8 FIG. a j a j a j a j At operation, the tape is partitioned longitudinally into a plurality of zones based on the size of the peak filter array created in operationofand on the calculated servo parameters, like shown in. One peak of the peak filter array corresponds to one zone.illustrates a tapebeing partitioned into a plurality of zones-, according to one embodiment. The zones-may have different sizes, like shown in, or the zones-may all be the same size. The zones-have range in size from about 6 mm to about 18 mm.

356 816 814 812 812 358 814 812 812 812 812 816 816 816 800 a j a j a j 6 6 FIGS.A-B At operation, data write gaps(one shown for clarity purposes) are created at each boundarybetween each zone-. At operation, servo control parameters are updated as needed when the tape head crosses each boundary. The servo parameters are updated based on the LPOS of the peak filters in the peak filter array within each zone-and/or a speed of the tape. Thus, the servo control is specific to the disturbances detected within each zone-. The servo control parameters may include tape speed, skew or tilt of the tape head, and the parameters of servo control filters of. The write gapsmay range in size of less than about 15 mm, and the size of the write gapsis based on the amount of time needed for the servo heads to be updated with the zone-specific servo parameters (i.e., a settling time of servo control). The data write gapsrepresent write inhibit violations where data is not stored to the tapedue to the changing of servo parameters, as doing so may cause data written on adjacent tracks to be unintentionally overwritten.

9 FIG. 8 FIG. 900 816 800 illustrates a graphshowing the position error signal (PES) of a tape head versus micro-seconds during a data write gapof the tapeof, according to one embodiment.

900 800 800 816 800 As shown in the graph, the write inhibit violation of each data write gap lasts about 2 us to about 3 μs. During this time period, the PES of the tape head over the tapevaries greatly while the tape head is being updated with the zone-specific servo parameters. As such, data is not written to the tapewhere data write gapsoccur to preserve data written on adjacent tracks of the tape.

428 816 400 816 426 4 FIG. In some embodiments, a memory device(shown in) stores the LPOS of each write gap. The processoris further configured to compare a current LPOS of tape head to the LPOS of each write gapto update the servo control parameters. The servo controlleris then able to update the servo parameters based on the comparison of LPOS.

By utilizing the methods described above, the dynamic LTM of the tape drive can be reduced, resulting in a higher track density being achieved. As such, the track-following performance of the tape drive is improved. Furthermore, more data can be written to the tape.

In one embodiment, a tape drive comprises a take-up reel and a cartridge reel configured to have a tape coupled thereto, a tape head configured to write data to and read data from the tape, a first actuator, a second actuator, the first and second actuators each configured to actuate the tape head, and a processor configured to: perform a reel rotation per minute (RPM) disturbance profile identification detecting one or more disturbance points in the frequency domain of a position error signal (PES) along a length of a tape, acquire exact information of the disturbance points by applying a filter, acquire a longitudinal position (LPOS), frequency, and magnitude of the one or more disturbance points to create an updated disturbance profile identification of the disturbance points, use the updated disturbance profile identification to generate a peak filter array, the peak filter array being based off of the calculated servo parameters, and use the peak filter array to assist in instructing one or more of the first actuator and the second actuator to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during a read operation or a write operation.

The updated disturbance profile identification is based on a speed of the tape, a radius of the take-up and cartridge reels, a length of the tape, and a thickness of the tape. The reel RPM disturbance profile identification is performed in a factory setting. The reel RPM disturbance profile identification is performed one or more times at different tape speeds. The tape drive further comprises memory, wherein the peak filter array is stored in the memory. The tape drive further comprises a first actuator controller and a second actuator controller. The first actuator controller and the second actuator controller each individually comprise two or more peak filters used to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance. The first actuator is a voice coil motor actuator and the second actuator is a piezoelectric (PZT) actuator.

In another embodiment, a tape drive comprises a take-up reel and a cartridge reel configured to have a tape coupled thereto, a tape head configured to write data to and read data from the tape, a first actuator, a second actuator, the first and second actuators each configured to actuate the tape head, and a processor coupled to the tape head, the processor servo controller parameters, wherein the processor is configured to: perform a reel rotation per minute (RPM) disturbance profile identification detecting one or more disturbance points in a frequency domain of position error signal (PES), along a length of a tape, partition the tape longitudinally into a plurality of zones based on a peak filter array, wherein one peak of the peak filter array corresponds to one zone, create data write gaps at the boundaries between each of the zones, and update servo control parameters when the tape head crosses each boundary when writing data to or reading data from the tape, the updated servo parameters being based on the peak filter array and the LPOS.

The tape drive further comprises a servo controller. The servo controller comprises the updated servo parameters. The processor is further configured to a longitudinal position (LPOS), frequency, and magnitude of the one or more disturbance points to create an updated disturbance profile identification of the disturbance points, and use the updated disturbance profile identification to generate a peak filter array, the peak filter array being based off of the calculated servo parameters. The reel RPM disturbance profile identification is performed in a factory setting, and wherein the reel RPM disturbance profile identification is performed one or more times at different tape speeds. One or more of the plurality of zones have a different size. The processor is configured to compare a current longitudinal position (LPOS) of the tape head to the LPOS of each peak in the peak filter array calculated detected to update the servo control parameters. The first actuator is a voice coil motor actuator and the second actuator is a piezoelectric (PZT) actuator.

In yet another embodiment, a tape drive comprises a take-up reel and a cartridge reel configured to have a tape coupled thereto, a tape head configured to write data to and read data from the tape, a first actuator, a second actuator, the first and second actuators each configured to actuate the tape head, and a processor coupled to the tape head, the processor comprising servo controller parameters, wherein the processor is configured to: perform a reel rotation per minute (RPM) disturbance profile identification detecting one or more disturbance points in a frequency domain of position error signal (PES) along a length of a tape, acquire exact information of the disturbance points by applying a filter, acquire the longitudinal position (LPOS), frequency, and magnitude of the one or more disturbance points to create an updated disturbance profile identification, use the updated disturbance profile identification to create a peak filter array, use the peak filter array to assist in instructing one or more of the first actuator and the second actuator to move the tape head to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance during a read operation or a write operation, partition the tape longitudinally into a plurality of zones based on a size of the peak filter array, create data write gaps at the boundaries between each of the zones, and update servo control parameters when the tape head crosses each boundary when writing data to or reading data from the tape, the updated servo parameters being based on the calculated peak filter array.

The updated disturbance profile identification is based on a speed of the tape, a radius of the take-up and cartridge reels, a length of the tape, and a thickness of the tape. The reel RPM disturbance profile identification is performed in a factory setting, and wherein the reel RPM disturbance profile identification is performed one or more times at different tape speeds. One or more of the plurality of zones have a different size, and wherein a servo controller of the tape drive is configured to compare a current longitudinal position (LPOS) of the tape head to the LPOS of each peak of the peak filter array detected to update the servo control parameters. The tape drive further comprises memory. The peak filter array is stored in the memory. The first actuator controller and the second actuator controller each individually comprise two or more peak filters used to adjust a disturbance compensation to match a frequency and an amplitude of a disturbance. The first actuator is a voice coil motor actuator and the second actuator is a piezoelectric (PZT) actuator.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.